The present disclosure relates generally to wireless communication systems and, more particularly, to a method and apparatus for precise transmit power adjustment in a wireless communication system.
In any wireless communication system, there is a transmitter and a receiver. Regulatory bodies such as the Federal Communication Commissions (FCC) have established regulations that specify a maximum transmit power for the transmitter of various wireless communication systems. Some wireless communication systems such as cellular or mobile communication systems do not need to transmit radio signals at peak power levels since they have sufficient power allocated in their frequency spectrum to operate at long distances. Also, a small increase in the transmit power of these long range systems does not provide additional range that makes a difference in the overall coverage of the system, relatively speaking. As such, these systems do not require fine gain resolution for the power amplifier of the transmitter and thus, the power amplifier gain resolution is optimized to about 1.0 dB accuracy.
However, other wireless communication systems such as ultra-wideband (UWB) communication systems implemented in a wireless personal area network (WPAN) operate at very low power levels and spread the transmit power across a wide bandwidth. In order to maximize their communication range, UWB systems need to transmit radio signals at a maximum power level allowed by regulations. The process for accurately adjusting the transmit power in these wireless communication systems is difficult since the power amplifier of the transmitter does not have good gain resolution and dynamic range simultaneously. This process becomes even more complex due to variations of the power amplifier over temperature as well as voltage and process fluctuations. Therefore, it would be desirable to have a method and system for precise transmit power adjustments in UWB communication systems.